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Beagle 2 in HiRISE, Possible Targets
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post Dec 18 2008, 09:51 PM
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Well said, Stu.

It should also be noted that in engineering we sometimes learn more from failure than from success. Analysis of failure modes often refines (or even defines previously unknown) top-level system performance constraints and inevitably leads to better designs. In that light, B2 is still making a significant contribution to solve the fundamental engineering problem 'how to survive EDL on Mars'.

Certainly not as satisfying as a successful mission would have been, but nevertheless a net gain in human knowledge was realized from B2.


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sci44
post Dec 19 2008, 12:25 AM
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QUOTE (ugordan @ Dec 18 2008, 05:52 PM) *
In all fairness, you can't compare surface conditions to entry conditions both probes experienced. Huygens entered at what, 6 km/s and isn't that a typical Mars entry velocity, too?


According to the article, Beagle hit at mach 35, around 12 km/s - it detached prior to orbital insertion, to save MEX a bit of delta-V. For us lesser beings reading this thread, the wiki on atmospheric re-entry is actually pretty decent.

QUOTE (mcaplinger @ Dec 18 2008, 09:36 PM) *
Here's the Casani report for people who feel like reading it. Note section 6.2.2 in particular.

http://www.bnsc.gov.uk/5278.aspx


That is interesting - plenty of critisism but on aeroentry the report states "Both the quantity and quality of the work performed are outstanding."
They were asked to reduce weight from 108kg to 60kg in 1998, and less mass has to mean more susceptibility to any chaotic forces on entry.
On another thread on MEX/B2 I mooted the idea of sending Beagle-3 on an SEP first stage - it could be delivered to GTO as a mission of opportunity (like SMART-1), and take its time to spiral to Mars. An SEP stage would allow a larger delivered mass - indeed as a first ever use of such a delivery method for a planetary craft, it could be seen as a test mission. This time EDL comms would be a must too..

Only this time, instead of Blur, we should ask Monty Python to sponser the mission. Beagle, as part of its EDL, should broadcast "The Liberty Bell" during descent, with the big foot coming down at the time of its landing! smile.gif
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Paolo
post Jan 2 2009, 11:54 AM
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QUOTE (Sunspot @ Dec 17 2008, 09:23 PM) *
Beagle 2 may have tumbled to a fiery doom

http://www.newscientist.com/article/mg2002...fiery-doom.html


Journal of Spacecraft and Rockets paper now available for free
See the AIAA siteof the journal under Sample Issue.
There is also a paper on Stardust's reentry available for free


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rlorenz
post Jan 2 2009, 03:05 PM
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QUOTE (Paolo @ Jan 2 2009, 06:54 AM) *
Journal of Spacecraft and Rockets paper now available for free


Readers might also be interested in a review I did a couple of years ago on spin of
planetary probes (emphasis was on descent, rather than entry, but it touches on it
and summarizes the various spin rates and spin-separation-umbilical designs used.
http://www.lpl.arizona.edu/~rlorenz/spinjbis.pdf

I have to say in the process of researching this, I find it very difficult to find
*pre-Mission* calculations of release spin rates for entry vehicles. Notionally the
spin rate should be chosen based on angle of attack tolerance at the entry
interface (which in turn depends on targeting accuracy, as well as the moment
of inertia, the expected disturbance torques and the coast time) as well as
dynamic stability during the entry itself (the subject of this paper). While there
are always post-mission reconstructions etc., I haven't come across a paper
saying 'This is the spin rate we chose and this is why'. (Maybe because of fear
one gets it wrong..?)

This Beage/J.Spacecraft paper may be getting more attention than it deserves -
I can't see any obvious problems with it, but the main message is 'look, here is a
simulation that diverges in the transition regime'. It would be more useful to
show that the same simulation code yields survivable entries for MPF, MER etc.,
and to show what the 'correct' spin rate for Beagle should have been (if, indeed,
any spin rate would have worked....)

A complex problem, verging (as another poster noted) on a black art.
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sci44
post Jan 3 2009, 03:14 PM
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Well the Beagle 2 mission scientists (Pillinger, Smith) themselves remain sceptical of this new report.

(Pillingers quote at the end of that piece is priceless!)
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Guest_Zvezdichko_*
post Jan 3 2009, 09:09 PM
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By the way, while I respect you opinion, I think that you are wrong.

I have read the report and thousands of critical articles. The British team is very ambitious, but I have the feeling that they always blame the environment. Firstly, the big crater, secondly, the thin atmosphere.
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sci44
post Jan 3 2009, 11:24 PM
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QUOTE (Zvezdichko @ Jan 3 2009, 09:09 PM) *
By the way, while I respect you opinion, I think that you are wrong.

I have read the report and thousands of critical articles. The British team is very ambitious, but I have the feeling that they always blame the environment. Firstly, the big crater, secondly, the thin atmosphere.


Well, I am sure you could be right - there *could* be other engineering issues with Beagle-2 beyond "bad luck" factors like landing on the side of a crater, or the atmosphere being too thin. We will never know for sure without EDL data, and I would expect EDL comms would be high on the list for B3. I will not re-iterate everything else from this and other B2 threads - you can even consider sheer dead weight as being a factor - in 1998 the Beagle-2 team had to reduce the allowed probe weight from 108kg to 60kg - from pure engineering intuition, a lump of lead might be less susceptible to chaotic forces than a light object.. My real point is, why give up on the first go?

And at that point - you turned to discussing politics. That is a banned subject at UMSF. That has been deleted, as has the reply - Admin.
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djellison
post Apr 15 2009, 02:30 PM
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Something I learnt from Mark Sims (Beagle 2) last week. Beagle's parachute, which is the big clue I've been looking for in MOC and HiRISE imagery... was fairly transparent, and sort of beige.
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Phil Stooke
post Apr 15 2009, 03:41 PM
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That's going to make it a lot easier! smile.gif

Memo to future mission planners: make parachute visible...

Phil


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ElkGroveDan
post Apr 15 2009, 03:49 PM
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QUOTE (Phil Stooke @ Apr 15 2009, 07:41 AM) *
Memo to future mission planners: make parachute visible...


A discussion we were having last night


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If Occam had heard my theory, things would be very different now.
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djellison
post Apr 15 2009, 04:25 PM
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That's what triggered me to post this smile.gif
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Guest_PhilCo126_*
post Apr 16 2009, 06:54 AM
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Indeed parachutes should be made in Orange/White "Search & Rescue" color scheme otherwise these are untraceable.
Then again when these are tested, engineers are on the spot and don't have to search for it wink.gif
Take a look at this test, the parachute is well camouflaged:

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imipak
post Apr 16 2009, 09:06 PM
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I give up; what (and where) on earth is it?


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Hungry4info
post Apr 16 2009, 09:46 PM
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QUOTE (imipak @ Apr 16 2009, 03:06 PM) *
I give up; what (and where) on earth is it?


It's the Orion parachute test. The parachute failed. I don't know where it is though.


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ElkGroveDan
post Apr 17 2009, 02:09 AM
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It's not California, maybe Arizona or New Mexico by the look of the soil.


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